1. Field of the Invention
The present invention relates to a helical scan recording/reproduction apparatus and more particularly to a tape guide mechanism used in the rotary head unit thereof and a tape travel mechanism around the rotary head.
2. Description of the Prior Art
A tape guide mechanism used in a rotary head unit and a tape travel mechanism around it of a conventional helical scan recording/reproduction apparatus will be described below with reference to FIG. 5.
FIG. 5 is a front view of a cylinder 1. The cylinder 1 has a propeller type rotary head 3 comprising a plurality of heads between upper and lower drums 8 and 9. The upper and lower drums 8, 9 are of the stationary type. The cylinder 1 is inclined at a predetermined acute angle to a predetermined direction. A lead 14 having an upper end face 14a for regulating the widthwise position of a tape 4 is provided on the curved surface of the lower drum 9 of the cylinder 1. Pin-like stationary inclined guides 11 and 12 are respectively provided on base portions 11a and 12a at a tape entrance and a tape exit of the cylinder 1. These stationary inclined guides 11 and 12 are inclined at a predetermined angle to a predetermined direction. Alternatively, these guides may have a conical shape.
A rotary upright guide 10 is provided so as to rotate around a shaft 10d in the upstream side (i.e. at the tape entrance side) of the stationary inclined guide 11, and a rotary upright guide 13 is provided so as to rotate around a shaft 13d in the downstream side (i.e. at the tape exit side) of the stationary inclined guide 12. Upper flanges 10a and 13a for regulating the widthwise position of the tape 4 are respectively provided on the upper portions of the rotary upright guides 10 and 13, and springs 1Ob and 13b for adjusting the heights of the upper flanges 10a and 10b with respect to an upper edge 4a of the tape 4 are respectively provided on the lower portions of the guides 10 and 13. The rotary upright guides 10 and 13 can be rotated as the tape 4 travels.
The tape 4 normally travels in the direction of the arrow a to be subjected to recording/reproduction. The tape 4 horizontally travels along the rotary upright guide 10, and the flange 10a slightly holds down the upper edge 4a of the tape 4 downward, thereby regulating the position of the tape 4 in one widthwise direction (the direction of the arrow c in FIG. 5). When the tape 4 passes the stationary inclined guide 11, it obliquely travels and contacts the cylinder 1, and is wound around the cylinder 1 at a predetermined winding angle. A lower edge 4b of the tape 4 is brought into contact with the upper end face 14a of the lead 14 of the cylinder 1, and the tape 4 travels along the upper end face 14a of the lead 14, thereby regulating the position of the tape 4 in the other widthwise direction (the direction of the arrow d in FIG. 5).
The tape 4 which has passed over the cylinder 1 passes the stationary inclined guide 12, and then travels horizontally again. The upper flange 13a slightly holds down the upper edge 4a of the tape 4, thereby regulating the same widthwise position of the tape 4 as described in the flange 10a.
As described above, in the conventional tape guide mechanism, the two edges 4a and 4b of the tape 4 are statically regulated by the upper flanges 10a and 13a, and the lead 14. Therefore, a so-called tape path alignment adjustment must be executed by adjusting the positions of the screw-like upper flanges 10a and 13a using a screwdriver or the like and absorbing a change in height by the springs 1Ob and 13b. Since the widthwise position of the tape 4 can be regulated by this adjustment, the inclination angle between the circumferential rotating direction of the rotary head 3 and the longitudinal direction of the tape 4 can be kept constant, and tape compatibility with different recording and reproduction apparatuses can be obtained. Regulation of the tape travel height requires precise operations executed while monitoring a reproduction signal using reference tapes, and the tape compatibility is often unobtainable, depending on the adjustment state.
In the tape path alignment adjustment, when contact forces of the upper flanges 10a and 13a of the rotary upright guides 10 and 13 to the upper edge 4a of the tape 4 are too strong, the tape 4 is deformed at the upper and lower edges 4a and 4b. However, when the contact forces are too weak, the lower edge 4b is undesirably separated from the upper end face 14a of the lead 14. Therefore, the tape path alignment adjustment for obtaining preferable contact between the upper flanges 10a and 13a and the edge 4a of the tape 4 requires delicate operations, and is cumbersome.
Since the cylinder is rendered compact (its diameter is decreased) according to the reduction in size of the helical scan recording/reproduction apparatus, the winding angle of the tape on the cylinder is increased, and the winding angle of the tape on the stationary inclined guide is also increased. Therefore, since the frictional resistance between the stationary inclined guides 11 and 12, and the tape 4 is thereby increased during tape travel, the load on the tape drive motor is increased. However, as the recording/reproduction apparatus is reduced in size, the motor must inevitably be rendered compact. As a result, a compact motor having a large torque is ironically required. In order to suppress an increase in the frictional resistance, the intervals between the cylinder 1 and the stationary inclined guides 11 and 12 may be increased. However, this arrangement disturbs the reduction in size of the recording/reproduction apparatus.